This invention relates to a color proofing apparatus and a method of making a color proof, and in particular, to a method of making a color proof by exposing a silver halide color photosensitive material to light from a plurality of light sources of different wavelengths, on the basis of halftone dot image data which have been processed by an RIP (Raster Image Processor), and a color proofing apparatus employing the method.
In producing color prints, sometimes color correction is practiced at the stage of the original films; it has been put in practice that the objects for correction (color proofs) are prepared by using color-separated halftone dot original films which have been produced by color separation into a C (cyan) separation, an M (magenta) separation, a Y (yellow) separation, and a K (black) separation, and before making a proper printing plate, it is inspected whether or not an error is made in the layout, the colors, and the letters of the original films, to confirm the finished state of the printed objects beforehand.
In recent years, making color proofs has been practiced by employing a DDCP (direct digital color proof) method. For one of the techniques of the DDCP method, such one that a silver halide color photosensitive material is exposed to a combination of a plurality of light spots having different wavelengths respectively such as R, G, and B for example, on the basis of halftone dot image data of the respective color-separated halftone dot originals, to develop respective color dots of the above-mentioned C, M, Y, and K.
Incidentally, in recent years, by the spread of DTP (Desk Top Publishing) etc., an operation such that an image inputted from a scanner is edited and a page layout is conducted on a computer software has been generalized, and edition in a full digital way has become not so rare.
In such a process, for further making the efficiency higher, the following are practiced: image setter outputting to directly output image data that have been subjected to page edition to a film, CTP (Computer to Plate) outputting to carry out direct image recording on a printing plate, and further, CTC (Computer to Cylinder) process to carry out direct image recording on a printing plate wound on a cylinder of a printing machine.
In this case, there is a problem that carrying out proofing by prints or proofing by means of other proof materials through once outputting to a film or to a printing plate for the confirmation of the correction only results in ineffective use of films or printing plates and too many extra operations.
For that reason, in particular, in the process to carry out image making and editing in a full digital way by a computer as described in the above, a system for practicing direct color image outputting which is called DDCP (Direct Digital Color Proof) or DCP (Digital Color Proof) is required.
In such a DDCP system, before recording on a film for plate making by means of an image setter from digital image data processed on a computer, a final printing operation to directly make a printing plate by CTP, direct image recording on a printing plate wound on the cylinder of a printing machine by CTC, or the like is carried out, it is produced a color proof which reproduces the object of output expressed by a digital image having been processed on a computer, to confirm the pattern of the picture, the color tone, the letters and sentences, etc.
Further, in a correction process in such printing processes, proofs are produced and used mainly in the following three uses:
(1) The confirmation of mistakes in the inside of the operation site, that is, the inside correction;
(2) The outside correction to be submitted to the order making person and the designer for the confirmation of the finish; and
(3) The print sample to be submitted to the operator of the printing machine as the sample of the final printed object.
In these cases, in the use for the inside confirmation, and in a part of the outside correction use, from the requirement for shortening the delivery time, the cost reduction, etc., there are some cases where a material for proofing incapable of reproducing a halftone dot image, in other words, a print produced by a sublimation transfer method, or an outputted print by an ink jet or electrophotographic method is used as a proof for the confirmation of the outline; however, it is an actual situation that, for the confirmation of the reproducibility of highlight areas and the fine details, and the confirmation of the unsuitable interference of a halftone dot image called a moire produced in printing, a proof which reproduces printed halftone dots in a high fidelity is strongly required.
For such needs, it has begun to spread in recent years DDCP of a type in which an image formed on a sublimation transfer recording material or a heat-sensitive recording material by an image exposure using a high-power heat mode laser is transferred to a printing paper sheet; however, in this system, it makes a problem that the cost of the laser head is high, the equipment is high-priced, the material is also high-priced because of the utilization of a number of color image forming sheets, and the processes from image exposure to transfer are necessary for each of the number of colors, which requires a long time; there is a problem that it is difficult in respect of the cost and time to apply the method to all jobs, or to produce a number of duplicates as conventional print proofs.
Therefore, for an apparatus to make such a color proof, it is proposed an image recording apparatus having a drum provided with a plurality of through holes penetrating from the outer peripheral surface to the inside, and a rotation driving mechanism for rotating said drum, and carrying out an exposure in accordance with digital image signals as holding a photosensitive material on said drum which are being rotated by said rotation driving mechanism, to record a halftone dot image.
Incidentally, the employment of DTP has been in process of development in recent years, and it has become possible to overlap picture patterns freely by an image processing software on a personal computer. Therefore, images including black ink, in which black print and one or some of prints of other colors overlaps each other without being recognized by the user, are increasing.
In this case, on the display of a personal computer, the areas where a black separation and one or some of separations of other colors overlap each other all look as black-colored. Therefore, the user cannot notice the state that separations of other colors, which are actually unnecessary, overlap the black separation.
Further, also in DDCP, because an image having a black print and one or some of prints of other colors overlapping each other is expressed by a black color, the overlapping areas all look as black-colored; therefore, a user cannot notice the state that a black print and one or some of prints of other colors overlap each other.
However, when actual printing is carried out, because an area of only black print and an area having black prints and one or some of prints of other colors overlapping each other (hereinafter referred to as “black-overlaid print” in this specification) look different, the user can notice that unnecessary prints of other colors overlap the black print for the first time. That is, it was not until printing was practiced that the user noticed a mistake in the image processing stage; therefore, it has been usual that a big uselessness in operation time and various kinds of materials was produced.
This invention has been made in view of such problems, and it is its object to provide an image data outputting apparatus capable of discriminating between the case where a certain color is overlaid with black and the case where only black is present.
It is another object of the invention to actualize a method of making a color proof and a color proofing apparatus capable of discriminating between the area of only a black print and the area of a black-overlaid print.